Ultra-violet liquid processing device with the prior art comprises a lamp holder installed with a UV lamp, as well as a liquid processor for holding the liquid to be purified. After the liquid to be purified enters the liquid processor, it is radiated by a UV lamp, and bacteria and algae in the liquid are killed under the UV radiation. Thus, liquid bactericidal and algae removal treatment is realized. The liquid after bactericidal and algae removal treatment discharges from the liquid processor. A sealing element is arranged between the said lamp holder and the liquid processor, and the said lamp holder is assembled to the liquid processor by virtue of threads or a cassette keel. UV liquid processing device is sealed by virtue of the extrusion force between the lamp holder and the liquid processor as well as the sealing element. To ensure the reliable seal, the ultra-violet liquid processing device with the prior art is also arranged with a prompt structure, so that users can confirm whether or not the device is assembled in place, namely sealed. However, the said prompt structure with the prior art is not obvious enough, and role of the prompt structure can only actually be worked when users pay attention to the sealing problem inwardly, so the said prompt structure is not the substantive structure ensuring assembly in place. If users fail to take notice of the prompt information of whether or not the lamp holder at the prompt structure is assembled in place due to negligence, it is unable to ensure that the said lamp holder is really assembled in place and reliably sealed. Obviously, if the lamp holder can't be assembled in place, it can't be reliably sealed, leading to leakage of liquid in the liquid processor, lowering liquid processing efficiency.
Besides, in the operation process, the situation that the lamp holder is directly removed from the liquid handler without disconnecting liquid source due to negligence is easy to occur. Under such situation, leakage of the liquid to be purified will also occur, reducing liquid processing efficiency. Nevertheless, project is not taken for the UV liquid processing device with the prior art, so as to avoid the occurrence of such situation.